Kusasalethu is located on the north-western margin of the Archean Witwatersrand Basin, one of the prominent gold provinces in the world. There are seven gold-bearing conglomerates within the mining right area, of which only the Ventersdorp Contact Reef (VCR) is economically viable. Kusasalethu is situated in the West Wits Basin and mines the Ventersdorp contact reef as its main orebody. The Ventersdorp Contact Reef facies model at Kusasalethu is based on the paleotopographic or slope and terrace model. Nine facies types have been recognised at Kusasalethu – eight sedimentological and one structural. Four of the facies are thick, high-grade, geologically distinct reef terraces separated from one another by a thin low-grade slope reef. The sand-filled channel is a thick low-grade facies. The Sandy Terrace Complex is found on the same elevation as the Terrace Complex but is essentially a pebbly quartzite with no grade. The Mondeor conglomerates have been identified sub-cropping against the Ventersdorp Contact Reef in stopes in certain areas and have been delineated as separate facies in these areas. The Elsburg conglomerates, found on the western side of Kusasalethu, form the footwall to the Ventersdorp Contact Reef and are part of the Turffontein Supergroup. It is a predominantly polymictic matrix-supported conglomerate of well-packed and moderately sorted, sub-rounded smoky (80%), black-grey (15%) quartz pebbles, chert (3%) and some elongated shale pebbles (2%). The matri ........

Kusasalethu is a mature, deep-level mine. The mine comprises twin vertical and twin sub-vertical shaft systems, and uses conventional mining methods in a sequential grid layout. Mining is conducted to a depth of 3 388m and is Harmony’s deepest mine. Access to the orebody is gained through a twin shaft system from surface to 73 level. The twin sub shaft system extends from 73 level to 115 level. The VCR horizon is extracted at Kusasalethu, and mining is conducted over five levels (98 level to 113 level) using SGM techniques. Due to the current mining depths at Kusasalethu, the SGM method with backfill and pre-conditioning is used. The SGM method is preferred due to the variability of the VCR orebody with respect to value, and the seismic risk associated with deep level mining. The mining sequence used for breast mining is a V-shaped configuration, colloquially referred to as the “inverted Christmas tree”. An underhand face configuration is adopted when mining towards the west, and an overhand face configuration when mining towards the east. The SGM method makes use of dip pillars and reduced mining spans with pre-developed tunnels, aimed at further control of stresses experienced during rock movement. Primary development is done off-reef (in waste rock), while secondary development is done on-reef (in the mineralised zone). The 10m-diameter rock/ventilation shaft was initially sunk to 2 195m and the man/material shaft to 2 127m. By June 1984, a 10m-diameter sub-vertical ........

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